💊 Chemical information

Pharmacopoeias.

In Eur. and US. Eur. also includes a form for homoeopathic preparations. Swiss also includes monographs for hypericum (fresh flowering tops) and hypericum oil.

Ph. Eur. 6.2 (St. John’s Wort).

Oral contraceptives.

For reports of a possible interaction between St John’s wort and oral contraceptives. Verapa m i l. For details of a possible interaction between St John’s wort and verapamil.

Xanthines.

For details of a possible interaction between St John’s wort and theophylline.

💊 Uses and Administration

Herbal preparations containing St John’s wort are used, frequently for self-medication, in the treatment of depression. Such preparations are also promoted for the treatment of other nervous disorders such as insomnia and anxiety, particularly if associated with the menopause. St John’s wort oil has also been used as an astringent. Hypericin, a major constituent of St John’s wort, has been investigated as an antiviral in the treatment of HIV infection and AIDS (but see Antiviral Action, below). The amount of active constituents can vary between different preparations and doses depend on the preparation being used.

Homoeopathy.

St John’s wort has been used in homoeopathic medicines under the following names: Hypericum; Hypericum perforatum; Hypericum perforatum ex herba; Hypericum, herba; Hyper.

Depression.

St John’s wort extracts are widely used in some countries for the treatment of depression. Two systematic reviews1,2 of randomised controlled studies found St John’s wort extracts to be more effective than placebo in the treatment of mild to moderate depressive disorders. However, the results of the more recent review2 also suggested that St John’s wort extracts were only of minor benefit in patients with major depression and probably of no benefit in those with a prolonged history of the condition; in addition, there was no evidence of effectiveness in severe depression. The authors of this review commented that recent placebo-controlled studies tended to show less favourable results for St John’s wort than older studies. It was considered that the heterogeneous findings were due partly to overestimation of effects in some smaller, older studies, and partly to the variable efficacy of St John’s wort extracts in different patient populations; non-publication of negative studies was not thought to have played a major role. The efficacy of St John’s wort compared with standard antidepressants has also been reviewed and found to be comparable.2However, this finding should be interpreted with caution, not least because doses of the standard antidepressants used were at the lower end of the range in some studies. The mechanism of action of St John’s wort extracts in the treatment of depression remains unclear. Extracts contain at least 10 active principles. Hypericin, one of the major constituents of St John’s wort, was first thought responsible for the antidepressant effect since it had an inhibitory action on monoamine oxidase in vitro. However it was later shown that this action was, at best, weak and it is now generally believed that monoamine oxidase inhibition is not responsible for the antidepressant effect of St John’s wort. More recent studies have suggested that hyperforin may be one of the major constituents responsible for the antidepressant effect.3 Although the evidence is mainly from in vitro studies, hyperforin inhibits the reuptake of several major neurotransmitters including serotonin, dopamine, and noradrenaline.4